1. Field of Invention
The field of invention relates generally to tunable lasers and, more specifically but not exclusively, relates to a thermally tuned filter having a pre-stressed membrane.
2. Background Information
Networks provide the infrastructure for many forms of communication. LANs (Local Area Network), WANs (Wide Area Network), MANs (Metropolitan Area Network), and the Internet are common networks. Optical networks are growing in popularity as more optical fiber is deployed. Optical transmissions offer higher bandwidth and less susceptibility to electromagnetic interference than transmissions over copper cable.
Wavelength Division Multiplexing (WDM) increases the capacity of optical fiber. WDM involves sending two or more optical signals having different wavelengths through an optical fiber. The optical signals are separated by wavelength at the receiving end. WDM allows increasing the capacity of an optical network without increasing the amount of optical fiber. Dense Wavelength Division Multiplexing (DWDM), which is a higher-capacity version of WDM, is also becoming popular in optical communication systems.
Tunable lasers are useful in WDM systems because they alleviate the need to have a separate source laser for each wavelength to be transmitted on an optical fiber. Tunable lasers have the ability to change the wavelength of their outputted optical signal. Tunable lasers are also useful in optical packet-switched networks where data is sent in packets on different wavelengths. However, components of a conventional tunable laser are susceptible to failure from vibration, shock, and other stresses that may occur during assembly and deployment of the laser.